This invention relates to container carrying vehicles and, more particularly, to such vehicles comprising an outer rigid U-shaped frame connected for towing to a tractor unit and supporting an inner rigid U-shaped frame with parallel sides provided with members for picking up and transporting a generally open-ended load-carrying receptacle.
Container carrying vehicles of this kind include an outer rigid frame with parallel legs supported by road wheels and interconnected at their forward ends by a transverse frame member to form a U-shaped frame connectable to a tractor unit. The outer frame supports an inner rigid U-shaped frame having parallel sides and an open end. The sides support horizontal flange members at about the ground level such that the vehicle may readily be backed into position to pick up and transport a load-carrying receptacle. Hydraulically operated power means are typically provided for moving the inner U-shaped frame upwardly from a lower end position to an upper end position for transporting the load-carrying receptacle. Further actuation of the hydraulic power system tilts the inner U-shaped frame and the load-carrying receptacle thereon, thereby to dump the contents from the receptacle.
A vehicle of the foregoing type is disclosed in Andersson U.S. Pat. No. 3,520,429. The vehicle therein disclosed has vertical guides at each of the rear end portions of the legs of the outer U-shaped frame for guiding carriages provided with pivot pin supports for pivotally supporting the adjacent ends of the legs of the inner U-shaped frame. The vehicle is further provided with hydraulically operable power means for moving the forward and rearward ends of the inner U-shaped frame between a lower end position and an upper end position and subsequently, the forward end of the inner U-shaped frame further above its upper end position to tilt the inner U-shaped frame about the pivot axis of the leg-supporting pivot pins. In this manner the inner frame is adapted to empty the load-carrying receptacle.
Vehicles of the type disclosed in the aforementioned patent, however, require separate front and rear hydraulic hoists. They further require separate controls for the forward and rearward hoists to control the lifting of the forward and rearward ends of the inner U-shaped member to raise and/or lower the same and to achieve a satisfactory position for transporting the load-carrying receptacle.
It is thus an object of the present invention to provide a container-carrying vehicle of the above-mentioned type that will obviate the necessity of providing independent front hoists.
It is a further object of the present invention to provide such a vehicle wherein the rear hoists interact with dumping cylinders automatically to achieve a desirable transport position for the receptacle when the inner U-shaped frame is raised from its horizontal pick-up position to its receptacle-transporting position.
It is a further object of the present invention to provide a vehicle of the above type with means that will achieve a forwardly tilted travel position automatically when the inner U-shaped frame is raised from its horizontal ground-level position to its travel position, thereby to prevent premature discharge of cargo from the receptacle.
It is a still further object of the present invention to provide a vehicle of the above type wherein the rear hoists provide a large vertical displacement of the rear end of the inner U-shaped frame for a lesser displacement of the hoists themselves.
It is a still further object of the present invention to provide latching and restraining mechanisms which require no operator controls, but which utilize the weight of the receptacle to restrain the same during dumping and which mechanisms automatically release under the influence of gravity upon resumption by the receptacle of its forwardly tilted travel position.
These and other objects and advantages of the invention are achieved with the vehicle of the present invention. The vehicle is provided with rear hoists mounted on each leg of an outer U-shaped frame. The rear hoists are connected to carriage means adapted to travel in vertical guides and which carriage means include pivot pin means for supporting the adjacent ends of the sides of an inner U-shaped frame at first pivot support points positioned adjacent the bottoms of such ends. The rear hoists are adapted to raise the first pivot support points from a lower end or ground level position of the inner frame to an upper end position thereof. The rear hoists are connected to the carriage means by chains entrained over pulleys mounted at the upper ends of the hoists, whereby extension of the hoists a given distance raises the adjacent ends of the inner U-shaped frame an amount equal to twice such distance.
The vehicle further includes hydraulic dumping means pivotally attached at one end to each of the sides of the inner U-shaped frame at second pivot support points disposed forwardly of and vertically above the first pivot support points. The hydraulic dumping means comprise hydraulic power devices which are pivotally attached at their other ends to third support points on the adjacent ends of the legs of the outer U-shaped frame. The third support points are positioned at the same horizontal level as the second pivot support points on the sides of the inner U-shaped frame when the latter is in its lower end or ground level position.
The hydraulic dumping means pivot about the third support points on the legs of the outer U-shaped frame and the second pivot support points on the sides of the inner U-shaped frame rotate upwardly about the third support points as the rear hoists raise the first pivot support points from their lower end position on the inner U-shaped frame to their upper end position. In this manner the inner U-shaped frame is simultaneously elevated and rotated by the action of the rear hoists, whereby the inner frame is automatically tilted forwardly downwardly in its upper end or travel position. Further extension of the hydraulic dumping means tilts the inner U-shaped frame about its first pivot support points to empty cargo from the receptacle carried thereby.
The invention further includes latching and restraining mechanisms which restrain the receptacle during dumping and automatically release the same under the influence of gravity upon the resumption of the forwardly tilted travel position. Such means include pockets in a lower surface of the load-carrying receptacle adjacent pick-up members on the sides of the inner U-shaped frame, each of such pockets being provided with a projection extending inwardly from its forwardly disposed end. A latch mounted on each pick-up member is positioned beneath each pocket when the inner U-shaped frame is positioned fully beneath the receptacle. Each latch has a detent adapted to engage the projection to prevent the receptacle from sliding rearwardly with respect to the inner U-shaped frame when the latter is tilted to its dumping position.
The invention further includes a pocket in the forward end of the receptacle having a lower surface generally parallel to the base thereof. A pawl member pivotally attached at its upper end to the forward end of the inner U-shaped frame is spring-biased away from such forward end to project into the pocket when the inner U-shaped frame is positioned fully therebeneath. The pawl member is provided with a notch in its forward face. A pendulum member is pivotally mounted on the forward end of the inner U-shaped frame forwardly of the pawl member. The pendulum member is adapted to hang free of the pawl member when the inner U-shaped frame is in both its lower ground level and upper travel positions. The pendulum member, however, rotates into the notch in the forward face of the pawl member when the inner U-shaped frame is further tilted about the first pivot support points, thereby to lock the pawl member into engagement with the lower surface of the pocket.
When the inner U-shaped frame is returned to its travel position by retracting the hydraulic dumping means, the pendulum member swings away from the pawl member, permitting the latter to be released from the pocket. The receptacle slides forwardly on the inner U-shaped frame to release itself from the latches engaging the lower pockets. Thus, when the inner U-shaped frame is lowered by the rear hoists to its horizontal ground level position, the receptacle can be readily disengaged therefrom by driving the vehicle forwardly with the inner U-shaped frame in such horizontal ground level position.